Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rituximab is routinely used for the treatment of neoplasia, although the mechanism of action remains uncertain. In the current study, CD20-induced apoptosis was investigated with a panel of anti-CD20 monoclonal antibodies (mAb) in a wide range of cell lines. A hierarchy of mAb activity was apparent, with the B1 mAb generally the most potent. Apoptosis through CD20 was dependent on the nature of mAb binding and correlated with the extent of homotypic cell adhesion induced. However, using anti-CD20 mAb, which vary in the extent to which they redistribute wild-type and mutant CD20 molecules to membrane rafts, we showed that CD20-induced apoptosis was independent of translocation to TX-100 insoluble rafts. Using crmA-transfected cells and caspase inhibitors, we showed that phosphatidylserine translocation and mitochondrial permeability transition evoked during CD20-induced apoptosis appeared caspase independent. Furthermore, in cytoplasts which lack mitochondria and in Bcl(2)-transfected cells, phosphatidylserine was still translocated to the cell surface after CD20 stimulation. Together, these data imply that CD20 can evoke apoptosis without the involvement of mitochondria and caspases and irrespective of redistribution into TX-100 insoluble membrane rafts.
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PMID:CD20-induced lymphoma cell death is independent of both caspases and its redistribution into triton X-100 insoluble membrane rafts. 1450 Mar 84

The main treatment modalities for lymphoma in the past decade have been radiation therapy and chemotherapy. Recently, molecular engineering provided humanized antibodies with promising clinical activity, and rituximab is the first commercially available antibody. This anti-CD20 monoclonal antibody (MoAb) showed little toxicity and demonstrated excellent clinical activity. Given as a single agent, it induces a high-response rate even in pretreated low-grade non-Hodgkin's lymphoma, the effect being higher if administered for a prolonged period of time. Its action is synergistic with chemotherapy, and combination treatment could improve survival in patients with aggressive lymphomas. Rituximab also demonstrated the ability to clear tumor cells from the circulation, allowing for an in vivo purging effect in the setting of peripheral stem cell collection and transplantation. Still, a number of issues related to its use need to be addressed, such as optimal dose and schedule and the situations in which rituximab should be given as a single agent or in addition to chemotherapy or other drugs, such as other MoAbs or interferons. We also need to understand when rituximab should be used in first-line treatment, with which type of chemotherapy the combination is most cost-effective, and patient population that will benefit most from this antibody treatment.
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PMID:Overview of antibody therapy in B-cell non-Hodgkin's lymphoma. 1455 70

Paraneoplastic pemphaigus (PNP) is a rare autoimmune mucocutaneous blistering disease that is commonly associated with underlying B-cell neoplasms. There is no standard therapy for PNP. Potent immunosuppression has been the only potentially effective treatment in the setting of malignancy because there is no correlation between tumor burden and activity of disease. Two recent case reports have noted the resolution of lesions of PNP after treatment of the underlying CD20+ B-cell lymphomas with rituximab. Rituximab is an anti-CD20 antibody that has had some success in treating proliferative B-cell disorders. We report a case of PNP in the setting of B-cell lymphoma that did not respond to this novel therapy, and discuss rituximab's putative mechanism of action along with the clinical settings in which this novel therapy may prove useful in the treatment of PNP.
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PMID:Using rituximab (anti-CD20 antibody) in a patient with paraneoplastic pemphigus. 1455 7

We present a primary cutaneous follicle center cell lymphoma (PCFCCL) patient who was successfully treated with Rituximab, a new anti-CD20 monoclonal antibody. A thirty-two-year-old male developed two asymptomatic tumors on the scalp. Histopathologically, the tumors were composed of diffuse and nodular infiltration of centrocytes and centroblasts. Immunohistopathologically, the tumor cells stained positively with anti-CD20 antibody and anti-kappa antibody, but not with anti-CD5, anti-CD10, or anti-Bcl-2 antibody. Radiation therapy is effective in treating PCFCCL; however, it usually results in the permanent loss of hair. This patient was treated with Rituximab and CHOP, and achieved a complete remission. He has had no recurrence in more than 12 months and no permanent loss of hair on the scalp.
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PMID:Primary cutaneous follicle center cell lymphoma of the scalp successfully treated with anti CD20 monoclonal antibody and CHOP combination therapy with no subsequent permanent loss of hair. 1457 59

The tumor-killing mechanisms available to monoclonal antibodies (mAbs; e.g., antagonism of growth factor receptors, antibody-dependent cell-mediated cytotoxicity) limit efficacy. Previous studies suggested that i.v. beta-glucan might function as an adjuvant for antitumor mAbs. beta- Glucan had been shown to function via the iC3b-receptor complement receptor 3 (CR3; CD11b/CD18) thereby enhancing leukocyte killing of tumor cells coated with iC3b via naturally occurring antitumor antibodies. Therapy with beta-glucans was limited by levels of natural antibodies and by tumor escape through elimination of antigen-positive cells. Accordingly, it was hypothesized that beta-glucan responses could be improved by combined administration with antitumor mAbs. Five tumor models were explored in BALB/c or C57Bl/6 mice using tumors that expressed either high levels of naturally occurring antigens (e.g., G(D2) ganglioside) or recombinant human MUC1. In comparison with antitumor mAb or beta-glucan alone, combined treatment with mAb plus beta-glucan produced significantly greater tumor regression in all models that included mammary, s.c., and hepatic tumors. Tumor-free survival only occurred in models that incorporated stable expression of the target antigen. beta-Glucan enhancement of the mAb tumoricidal response did not occur in mice deficient in either leukocyte CR3 (CD11b(-/-)) or serum C3, confirming the requirement for CR3 on leukocytes and iC3b on tumors. Granulocytes appeared to be primarily responsible for tumoricidal activity, because beta-glucan therapeutic responses did not occur in granulocyte-depleted mice. These data suggest that the therapeutic efficacy of mAbs known to activate complement (e.g., Herceptin, Rituxan, and Erbitux) could be significantly enhanced if they were combined with beta-glucan.
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PMID:Beta-glucan functions as an adjuvant for monoclonal antibody immunotherapy by recruiting tumoricidal granulocytes as killer cells. 1469 21

Rituximab has become a staple in the management of B-cell non-Hodgkin's lymphoma, but it has limited activity as a single agent, with responses in about half of patients with recurrent follicular and low-grade lymphoma. Radioimmunotherapy (RIT) may surmount inherent or acquired antibody resistance by targeting a radionuclide to tumor cells. This strategy is particularly appealing for B-cell lymphoma because CD20 affords an outstanding target and lymphomas are inherently radiosensitive. The efficacy and safety of RIT have been established in the treatment of relapsed or refractory indolent non-Hodgkin's lymphoma, and yttrium 90 ibritumomab tiuxetan (Zevalin; Biogen Idec Inc, Cambridge, MA) was the first RIT agent to be approved by the US Food and Drug Administration. This supplement to Seminars in Oncology seeks to present hematologists and medical oncologists with the most recent developments in RIT with (90)Y ibritumomab tiuxetan for non-Hodgkin's lymphoma, to clarify the role of the medical oncologist in the administration of the ibritumomab tiuxetan regimen, to indicate how and when RIT with (90)Y ibritumomab tiuxetan may most successfully be integrated into the continuum of treatment for patients with B-cell lymphoma, and to describe ongoing clinical trials with (90)Y ibritumomab tiuxetan in B-cell lymphomas.
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PMID:Future directions in radioimmunotherapy for B-cell lymphoma. 1471 Apr 1

Mouse, chimeric, humanized and human monoclonal antibodies (MABs) are all in use for treatment of human cancer. Unconjugated antibodies have a complex mechanism of action, dependent on the nature of the target structure. Antibodies can activate the immune system (antibody-dependent cellular cytotoxicity [ADCC], complement-dependent cytotoxicity [CDC], induction of tumor immunity [idiotype network]). ADCC appears to be one of the most important immune effector functions. Antibodies may also induce apoptosis, cell cycle arrest, inhibition of cell proliferation as well as angiogenesis and metastatic spread. For most antibodies there is no clear dose-response relationship in vivo. The effect of antibodies can be enhanced by combination with chemotherapy and/or by agents which activate the immune system. The best therapeutic effect may be obtained if MABs are used early in the course of the disease. Rituximab (anti-CD20) was the first registered MAB for the therapy of follicular lymphoma. Impressive results have been seen in combination with CHOP chemotherapy (cyclophosphamide, doxorubicin, vincristine and prednisone) in follicular and high-grade lymphomas. In other non-Hodgkin's lymphoma subtypes, promising results are also seen in combination with chemotherapy. Trastuzumab (anti-Her2) is a breakthrough in the treatment of breast cancer in combination with chemotherapeutic agents. This antibody is also in clinical testing for adjuvant treatment. Alemtuzumab (anti-CD52) has shown impressive results both in refractory chronic lymphocytic leukemia and as up-front therapy. There are many other antibodies in late stages of testing for registration. Interesting MABs include cetuximab (anti-epidermal growth factor receptor [EGFR]), especially in combination with radiotherapy in head and neck cancer; ABX-EGF (anti-EGFR) in renal carcinoma; bevacizumab (anti-vascular endothelial growth factor) in several solid tumors. Antiepithelial cell adhesion molecule antibodies show promise in combination with chemotherapy in the adjuvant setting of colorectal carcinoma. It is estimated that about 20 antibodies will be in clinical use by the year 2010.
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PMID:Monoclonal antibodies in human cancer. 1498 43

Recent advances in molecular biology have led to the development of selective molecular targeting agents for genes involved in cell proliferation, apoptosis, and angiogenesis in cancer cells. The current success of molecular targeting therapy is shown by: imatinib mesylate (STI571, Gleevec), targeted to the Bcr/Abl fusion protein derived from a translocation between chromosomes 9 and 22 in chronic myelogenous leukemia; rituximab (Rituxan), a monoclonal antibody to CD20 used in non-Hodgkin's lymphoma; trastuzumab (Herceptin), a chimeric monoclonal antibody to HER-2 used in breast cancer; and gefinitib (ZD1839, Irresa), a tyrosine kinase inhibitor of the epidermal growth factor receptor used in non-small cell lung cancer. The superior therapeutic efficacy of these molecular targeting agents over traditional chemotherapy has been shown by the survival benefit achieved for patients with advanced or recurrent cancers. Although the precise molecular mechanisms by which these agents produce or enhance an antitumor effect, alone or in combination with anticancer drugs, are not known, the specific inhibition of target genes critically involved in tumor progression and metastasis by the agent is clear. However, further studies to determine which patient groups and anticancer drugs are appropriate for combination therapy with these molecular targeting agents are needed. Herein, we discuss the current status and potential for overcoming drug resistance in solid tumors and focus on the differential features of the tumor microenvironment in solid and hematologic malignancies.
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PMID:Changes in therapy for solid tumors: potential for overcoming drug resistance in vivo with molecular targeting agents. 1505 42

We have recently reported that Rituximab (anti-CD20) sensitizes drug-resistant 2F7 and 10C9 B Non-Hodgkin's lymphoma (NHL) cell lines to the apoptotic effects of various chemotherapeutic drugs by downregulation of IL-10 and Bcl-2 expression. The mechanism by which Rituximab induces downregulation of IL-10 was examined. We hypothesized that Rituximab may inhibit p38 MAPK activity that regulates IL-10 expression via Sp1. Treatment of 2F7 cells with Rituximab or the p38 inhibitor SB203580 inhibited the constitutive p38 MAPK activity and resulted in the inhibition of Sp1, IL-10, STAT3, and Bcl-2. Inhibition of the Src-family PTKs, Lyn, and Src-family PTKs upstream signaling molecules of the p38MAPK pathway, by PP2, a specific Src-family kinase inhibitor, resulted in the inhibition of p38MAPK and IL-10 expression. In addition to p38 MAPK, Rituximab also inhibited NF-kappaB activity. Inhibition of the Src PTKs, MAPK, and NF-kappaB activities by Rituximab or by specific chemical inhibitors sensitized the cells to CDDP-mediated apoptosis. The above signaling-mediated effects by Rituximab were observed with similar kinetics beginning at 1 h following treatment. Thus, altogether, these results demonstrate that signaling by Rituximab results in the inhibition of the p38MAPK pathway, which in turn inhibits the transcription of IL-10 via Sp1. Inhibition of the IL-10 autocrine/paracrine loop results in the inhibition of STAT3 activity and, consequently, inhibition of Bcl-2 expression and sensitization to drugs-apoptosis. Further, Rituximab-mediated signaling identifies several new intracellular targets in NHL that may be of potential therapeutic interest for the development of new drugs in the treatment of drug-refractory NHL tumor cells.
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PMID:Rituximab inhibits p38 MAPK activity in 2F7 B NHL and decreases IL-10 transcription: pivotal role of p38 MAPK in drug resistance. 1507 78

Immunotoxins are chimeric proteins consisting of a toxin coupled to an antibody. To date, several clinical trials have been conducted, and some are still ongoing, to evaluate their anti-tumor efficacy. In this view, we chemically constructed an anti-CD20 immunotoxin with the mAb Rituximab and the type 1 ribosome-inactivating protein (RIP) saporin-S6, designed for B cells non-Hodgkin's lymphoma (NHL) therapy. This immunotoxin showed a specific cytotoxicity for the CD20+ cell lines Raji and D430B, evidenced by inhibition of protein synthesis, evaluation of apoptosis and clonogenic assay. Upon conjugation, saporin-S6 increased its toxicity on target cells by at least 2 logs, with IC(50) values of 0.1-0.3 nM. The percentage of AnnexinV+ cells was over 95% in both cell lines treated with 10 nM immunotoxin. A complete elimination of Raji clones was reached with the 10 nM immunotoxin, whereas a mixture of free RIP and mAb gave about 90% of clonogenic growth. Rituximab/saporin-S6, at 10 nM concentration, also induced apoptosis in 80% of lymphoma cells from NHL patients. Moreover, sensitivity of Raji to Rituximab/saporin-S6 was augmented when cells were coincubated with Fludarabine. The synergistic toxic effect of the two drugs led to a total elimination of the neoplastic population.
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PMID:The conjugate Rituximab/saporin-S6 completely inhibits clonogenic growth of CD20-expressing cells and produces a synergistic toxic effect with Fludarabine. 1510 91


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